Coordinated interference mitigation and cancelation

ABSTRACT

A method includes receiving at user equipment an indication of a subset of scheduling constraints for interference mitigation and cancelation and performing interference mitigation and cancelation utilizing the subset of scheduling constraints.

RELATED APPLICATION

This application claims priority to U.S. Provisional Application Ser.No. 61/843,826 (entitled ADVANCED WIRELESS COMMUNICATION SYSTEMS ANDTECHNIQUES, filed Jul. 8, 2013) which is incorporated herein byreference in its entirey.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram illustrated intra-cell interference accordingto an example embodiment.

FIG. 1B is a block diagram illustrating inter-cell interferenceaccording to an example embodiment.

FIG. 2 is a block diagram illustrating limitations on jointly scheduledUEs according to an example embodiment.

FIG. 3 is a flowchart illustrating a method of performing interferencemitigation and cancelation according to an example embodiment.

FIG. 4 is a table of coordination combinations using a two bit indexaccording to an example embodiment.

FIG. 5 is an alternative table of coordination combinations using a twobit index according to an example embodiment.

FIG. 6 is a table of coordination combinations using a three bit indexaccording to an example embodiment.

FIGS. 7A and 7B are block diagrams illustrating inter-cell coordinationaccording to an example embodiment.

FIG. 8 is a block diagram of an example cell station according to anexample embodiment.

BACKGROUND

Interference is a serious issue in wireless cellular communications,especially as the cell size gets smaller and user equipment (UE) densitygets higher. It has been shown that interference mitigation andcancelation (IMC) techniques can be implemented at the UE side forbetter throughput and quality of service (QoS). Since signals fromintra-cell or inter-cell UEs are typically controlled and coded usingprivate scrambling or allocations, especially in existing releases, anUE can only do blind IMC by exhaustive search or by linear processingbased on statistics. This entails either high complexity or poorperformance for IMC.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawings.The same reference numbers may be used in different drawings to identifythe same or similar elements. In the following description, for purposesof explanation and not limitation, specific details are set forth suchas particular structures, architectures, interfaces, techniques, etc. inorder to provide a thorough understanding of the various aspects of theclaimed invention. However, it will be apparent to those skilled in theart having the benefit of the present disclosure that the variousaspects of the invention claimed may be practiced in other examples thatdepart from these specific details. In certain instances, descriptionsof well-known devices, circuits, and methods are omitted so as not toobscure the description of the present invention with unnecessarydetail.

Interference is a serious issue in wireless cellular communications,especially as the cell size gets smaller and user equipment (UE) densitygets higher. It has been shown that interference mitigation andcancelation (IMC) techniques can be implemented at the UE side forbetter throughput and quality of service (QoS). Since signals fromintra-cell or inter-cell UEs are typically controlled and coded usingprivate scrambling or allocations, a UE can only do blind IMC byexhaustive search or by linear processing based on statistics. Thisentails either high complexity or poor performance for IMC. This isbecause the number of possible combinations between resource allocation,PMI (precoding matrix indicator), and MCS (modulation coding scheme)etc., is a big number. By sending the UE some side information about theco-scheduled UE(s) or even cross-cell UEs, one expects to achieve betterIMC result. As a result, example embodiments enable network-assistedinterference cancelation and mitigation.

In various examples, intra-cell and inter-cell transmissions on theMCS/resource allocation level are coordinated. An associatedside-information transmission and coding method is provided fornotifying UEs, so that a more efficient and effective IMC is achieved.

In one embodiment, scheduling coordination is performed between MU-MIMO(multiple user multiple-input multiple-output) UEs in one cell and thecoordination across neighboring cells. When the base station(eNB—evolved node B) schedules a pair or more UEs in a cell for MU-MIMO,the combinations among MCS, precoding (PMI—precoding matrix indicator)and frequency-time resources are limited to a smaller number ofpossibilities. The combinations are narrowed and indexed using a fewbits, which will be sent to the UEs as a new type of DCI (downlinkcontrol indicator) for better IMC. In some example embodiments, theremay be more than MCS, PMI and frequency-time resources. One example ispower.

In cross-cell coordination, a slow coordination between cells ispresented which determines a set of frequency-time resource so thatneighboring cells can allocate interference-suffering UEs in thisregion. In this so-called ‘Interference Coordination Region’(IC-Region), a limited number of MCS/resource scheduling/PMI etc.,combinations are allowed. UEs scheduled in such region can assume thatthe interference signal has limited possible allocations on resourceallocation and/or MCS etc. This allows better IMC and betterinterference situation. Several specific options in encoding are alsoprovided.

FIGS. 1A and 1B illustrate two interference situations. Intra-cellinterference is illustrated at 100 in FIG. 1A, and involves interferencebetween different UE indicated at 102 and 104 in a single base station(eNB) indicated at 106. Inter-cell interference is illustrated at 110 inFIG. 1B, and involves interference between two base stations 112, 114 atone or more UEs indicated at 116. The sizes of the arrows indicaterelative signal strengths between the UEs and the cell stations. Thedesign for intra-cell coordination can be considered a special case ofthe inter-cell coordination in various examples. Note that limitingcombinations will gain overall in terms of system throughput especiallyat cell-edge UEs. This is because these UEs will not perform well withhigh MCS orders, fancy scheduling, or complicated combinations.

Example mechanisms provide intra-cell and inter-cell coordinationwithout much overhead. By carefully choosing the limited number ofcombinations, a better trade-off is achieved betweeninterference-cancelation performance of cell-edge UEs and overall systemthroughput.

In LTE, scheduling of a UE's transmission has many parameters such asmodulation order (e.g. QPSK/16QAM/64QAM), MCS (index of themodulation/coding combinations), PMI, resource allocations, transmissionmode, layers/ranks etc. We call this set of parameters the ‘schedulingparameters’. This creates a big search space for any UE that tries to dointerference cancelation or mitigation in a fine way.

In one example, a scheduling method for the eNB limits the number ofpossible combinations between co-scheduled UEs (e.g. MU-MIMO orcross-cell). This may be referred to as a subset of schedulingconstraints, which by definition, contains fewer constraints than arenormally available for use in performing interference-cancelationmitigation. In one embodiment, the scheduling constraint is onmodulation/TM (transmission mode)/MCS/PMI. The coordinated parametersmay be within a limited boundary of each other (as compared to thenumber of possibilities if there is no such coordination).

A UE may be notified by its eNB that it is under such a co-schedulingcoordination, by special signaling. A new DCI format with dedicated Kbits (e.g. 2 or 3) is used by the eNB to indicate the coordinationpattern, i.e. which limitations are to be enforced. This new DCI may bechanged at a sub-frame level.

At a high-level, such as RRC (radio resource control), with a slowerperiod, the mapping between the bits and the coordination patterns canbe changed. Neighboring cells can be coordinated over a backhaul (e.g.X2) in a much slower frequency for coordinating scheduling towards abetter IMC performance. Neighboring cells may agree on a specialresource region (IC-region) on the resource grid (e.g. a set of RBsacross certain subframes). UEs scheduled in this region may have a verylimited number of possible combinations of scheduling parameters. In afurther example, an eNB can provide UEs in the IC-Region moreinformation by using a new DCI as in the intra-cell coordination case.

Regarding to the possible combinations, once a UE (say UE0) is notifiedthat it is scheduled with interference-coordination, the followinglimitation on the jointly-scheduled UEs, as illustrated at 200 in FIG.2, is enforced:

1) Resource allocation of any co-scheduled UEs 210, 215 have only alimited number of starting points and scheduling patterns. For example,one option is to assume that co-scheduled UE RBs (radio bands) can onlybe totally overlapping or start, or in the case of UEs 220, 225 from themid-point 230 of UE0's RB allocation, and the RBs must be continuous;

2) Modulation orders of co-scheduled UEs are within a limited range,e.g. 0 (equal order) or 1. MCS orders can be assumed to be within acertain range, which can be inferred based on the new DCI message;

3) Transmission modes are within a limited number of combinations.

4) The number of co-scheduled layers should be limited. New DCI canspecify further limits on the number. E.g. no more than 2 or 4. Thisalso applies to the number of co-scheduled UEs.

In intra-cell design, the eNB has a set of coordination modes, sayModel, . . . , ModeJ. Each mode corresponds to a table of K items, witheach item being represented by an index. Each item limits the schedulingoptions of the joint-scheduled UEs. The coordinated properties include:RB allocation, modulation order, TM, number of co-scheduled UEs, numberof layers, etc.

A method 300 of performing interference mitigation and cancelationutilizing various resource allocation modes is illustrated in FIG. 3. At310, RRC signaling may be used to specify which mode is in effect. At315, in a control instruction (PDCCH), the coordination is instructed tothe UE by letting it know the item's index. At 320, based on the ‘mode’and ‘item index’, the UE limits the co-scheduling options, which helpsits interference mitigation in decoding. At 325, a UE can typicallyassume that all its co-scheduled UEs don't use 64QAM. (Because 64QAM isthe finest modulation order and like random Gaussian noise already.)

DCI may be used in two different options. In a first option, a privateDCI is sent to a co-scheduled UE as identified by the eNB. This optionallows a legacy UE who does not understand the new DCI to beco-scheduled. In a second option, a common DCI is multi-casted to allco-scheduled UEs. This control channel may be scrambled and coded usingsequences known to all these UEs.

Several design options may utilize at least 2 or 3 bits indicating thecoordination combinations. In one example, two-bit information is sent.Each such information indicates certain limitations on possiblecombinations. The emphasis is the case when the co-scheduled UEs havesimilar scheduling setup.

In one specific example illustrated in table form in FIG. 4 at 400, itis assumed that UE0 is the UE that received this new DCI. M(0) is themodulation order of UE0, and M(k) is for the coordinated UE(k). An indexcolumn 410 shows four entries, 0, 1, 2, and 3, corresponding to a twobit index. RB allocation is shown at 415. The RB allocation may changein the middle or switch once at a mid-point in this example. Modulationorder is shown at 420, and may be the same, or vary between M(0)−1 andM(0)+1 as illustrated. A TM (Transmission mode) 425 is shown the same asUE0 for each UE, as are the RS port positions at 430. A number ofco-scheduled UEs in column 435 varies between 1 and less than or equalto 4. A number of co-scheduled ranks at 440 may also vary between 1 andless than or equal to 4.

In a further option illustrated in table form at 500 in FIG. 5 a UE canassume that no 64QAM is used. Table 500 uses the same reference numbersas table 400 where the columns are the same. In addition, a powerdifference of ×dB is indicated at 510 and is a threshold number. Notmuch use of side information is made if 64QAM is utilized.

In a still further option, coordination betweenrank/RB/modulation/TM/#UEs is utilized as indicated at table 600 in FIG.6. The index 610 in this example is a three bit index havingcorresponding Arabic numbers 0 through 7, for a total of up to 8entries. RB allocation is illustrated at 615. Modulation order is shownat 620 and may be the same as UE0, the same as UE0 on all layers, varybetween M(0)−1 and M(0)+1, equal to M(0)−1 or M(0)+1, M(k)=M(0)+1,M(k)=M(0)−1 or M(0), M(k) less than or equal to M(0)+1 in variousexamples. In this example, the only difference between index 0 and index1 is that the latter allows two co-scheduled ranks. The term “alllayers” means that both layers' scheduling is subject to the sameconstraint. TM is indicated at 625 and may be the same as UE0 or legacy,the same as UE0 or legacy on all layers. PR port positions are indicatedat 630 and may be the same as UE0 or the same as UE0 on all layers. Anumber of co-scheduled UEs is indicated at 635 and may vary between 1and 4, with specific examples illustrated as 1, 2, and less than orequal to 4. Finally, the number of co-scheduled ranks at 640 may alsorange from 1 to 4, with specific examples illustrated as 1, 2, and lessthan or equal to 4.

A further option is that UE can assume that no 64QAM is used. Besidesthe above combinations, the following side information can be sent forbetter information compression. Side information 1: Total number ofUEs/Ranks scheduled. Side information 2: maximum variations of certainparameters between the UEs. E.g.|ModulationOrder(i)−ModulationOrder(j)|<=1, excluding 64QAM; or|MCS(i)-MCS(j)|<=3.

Inter-cell coordination may also be performed. The basic structure andsteps are illustrated in FIGS. 7A at 700 and in 7B. Neighboring cellsindicated at 710 and 715 exchange over X2 (or other backhaul channel)for coordinating IMC. Over X2, a dedicated resource region A at 720(freq+time) is designated as ‘interference-cooperationregion’(IC-region). In this IC-region 720, each cell's scheduling can beimplicitly or easily derivable by neighbors. Over a fixed period, e.g.200 ms, the neighboring cells 710, 715 synchronize again on IC-region A720 and the derivation mechanism (i.e. the scheduling constraints) forscheduling in A.

Scheduling alignment in IC-region 720: For a UE that gets scheduled inthe IC-region, it can infer that the scheduling coordination takeseffect. Parameters under coordination are similar as in the intra-cellMU-MIMO case.

There are many options of limiting the possible coordinationcombinations within IC-region. Several options are presented here,including all the UEs in region A can only use QPSK (phase-shiftkeying). In a further option, a UE's RB allocation starts from aspecified set of RBs (e.g. continuous) and/or with fixed length (e.g3/6/9RBs). This helps the neighbor UEs in blind interference cancelationand mitigation. In yet a further option, for each RB block, itstransmission is fixed to be say RANK1, 16QAM, a very limited number ofcombinations.

FIG. 8 is a block diagram of a specifically programmed computer systemto act as one or more different types of cell stations, including userequipment, small cell stations and macro stations. The system may beused to implement one or more methods according to the examplesdescribed. In the embodiment shown in FIG. 8, a hardware and operatingenvironment is provided to enable the computer system to execute one ormore methods and functions that are described herein. In someembodiments, the system may be a small cell station, macro cell station,smart phone, tablet, or other networked device that can provide accessand wireless networking capabilities to one or more devices. Suchdevices need not have all the components included in FIG. 8.

FIG. 8 illustrates a functional block diagram of a cell station 800 inaccordance with some embodiments. Cell station 800 may be suitable foruse as a small cell station, macro cell station, or user equipment, suchas a wireless cell phone, tablet or other computer. The cell station 800may include physical layer circuitry 802 for transmitting and receivingsignals to and from eNBs using one or more antennas 801. Cell station800 may also include processing circuitry 804 that may include, amongother things a channel estimator. Cell station 800 may also includememory 806. The processing circuitry may be configured to determineseveral different feedback values discussed below for transmission tothe eNB. The processing circuitry may also include a media accesscontrol (MAC) layer.

In some embodiments, the cell station 800 may include one or more of akeyboard, a display, a non-volatile memory port, multiple antennas, agraphics processor, an application processor, speakers, and other mobiledevice elements. The display may be an LCD screen including a touchscreen.

The one or more antennas 801 utilized by the cell station 800 maycomprise one or more directional or omnidirectional antennas, including,for example, dipole antennas, monopole antennas, patch antennas, loopantennas, microstrip antennas or other types of antennas suitable fortransmission of RF signals. In some embodiments, instead of two or moreantennas, a single antenna with multiple apertures may be used. In theseembodiments, each aperture may be considered a separate antenna. In somemultiple-input multiple-output (MIMO) embodiments, the antennas may beeffectively separated to take advantage of spatial diversity and thedifferent channel characteristics that may result between each ofantennas and the antennas of a transmitting station. In some MIMOembodiments, the antennas may be separated by up to 1/10 of a wavelengthor more.

Although the cell station 800 is illustrated as having several separatefunctional elements, one or more of the functional elements may becombined and may be implemented by combinations of software-configuredelements, such as processing elements including digital signalprocessors (DSPs), and/or other hardware elements. For example, someelements may comprise one or more microprocessors, DSPs, applicationspecific integrated circuits (ASICs), radio-frequency integratedcircuits (RFICs) and combinations of various hardware and logiccircuitry for performing at least the functions described herein. Insome embodiments, the functional elements may refer to one or moreprocesses operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage medium, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage medium may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagemedium may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. In these embodiments, oneor more processors of the cell station 800 may be configured with theinstructions to perform the operations described herein.

In some embodiments, the cell station 800 may be configured to receiveOFDM communication signals over a multicarrier communication channel inaccordance with an OFDMA communication technique. The OFDM signals maycomprise a plurality of orthogonal subcarriers. In some broadbandmulticarrier embodiments, evolved node Bs (NBs) may be part of abroadband wireless access (BWA) network communication network, such as aWorldwide Interoperability for Microwave Access (WiMAX) communicationnetwork or a 3rd Generation Partnership Project (3GPP) UniversalTerrestrial Radio Access Network (UTRAN) Long-Term-Evolution (LTE) or aLong-Term-Evolution (LTE) communication network, although the scope ofthe invention is not limited in this respect. In these broadbandmulticarrier embodiments, the cell station 800 and the eNBs may beconfigured to communicate in accordance with an orthogonal frequencydivision multiple access (OFDMA) technique. The UTRAN LTE standardsinclude the 3rd Generation Partnership Project (3GPP) standards forUTRAN-LTE, release 8, March 2008, and release 10, December 2010,including variations and evolutions thereof.

In some LTE embodiments, the basic unit of the wireless resource is thePhysical Resource Block (PRB). The PRB may comprise 12 sub-carriers inthe frequency domain×0.5 ms in the time domain. The PRBs may beallocated in pairs (in the time domain). In these embodiments, the PRBmay comprise a plurality of resource elements (REs). A RE may compriseone sub-carrier×one symbol.

Two types of reference signals may be transmitted by an eNB includingdemodulation reference signals (DM-RS), channel state informationreference signals (CIS-RS) and/or a common reference signal (CRS). TheDM-RS may be used by the UE for data demodulation. The reference signalsmay be transmitted in predetermined PRBs. In some embodiments, the OFDMAtechnique may be either a frequency domain duplexing (FDD) techniquethat uses different uplink and downlink spectrum or a time-domainduplexing (TDD) technique that uses the same spectrum for uplink anddownlink.

In some other embodiments, the cell station 800 and the eNBs may beconfigured to communicate signals that were transmitted using one ormore other modulation techniques such as spread spectrum modulation(e.g., direct sequence code division multiple access (DS-CDMA) and/orfrequency hopping code division multiple access (FH-CDMA)),time-division multiplexing (TDM) modulation, and/or frequency-divisionmultiplexing (FDM) modulation, although the scope of the embodiments isnot limited in this respect.

In some embodiments, the cell station 800 may be part of a portablewireless communication device, such as a personal digital assistant(PDA), a laptop or portable computer with wireless communicationcapability, a web tablet, a wireless telephone, a wireless headset, apager, an instant messaging device, a digital camera, an access point, atelevision, a medical device (e.g., a heart rate monitor, a bloodpressure monitor, etc.), or other device that may receive and/ortransmit information wirelessly.

In some LTE embodiments, the cell station 800 may calculate severaldifferent feedback values which may be used to perform channel adaptionfor closed-loop spatial multiplexing transmission mode. These feedbackvalues may include a channel-quality indicator (CQI), a rank indicator(RI) and a precoding matrix indicator (PMI). By the CQI, the transmitterselects one of several modulation alphabets and code rate combinations.The RI informs the transmitter about the number of useful transmissionlayers for the current MIMO channel, and the PMI indicates the codebookindex of the precoding matrix (depending on the number of transmitantennas) that is applied at the transmitter. The code rate used by theeNB may be based on the CQI. The PMI may be a vector that is calculatedby the cell station and reported to the eNB. In some embodiments, thecell station may transmit a physical uplink control channel (PUCCH) offormat 2, 2a or 2b containing the CQI/PMI or RI.

In these embodiments, the CQI may be an indication of the downlinkmobile radio channel quality as experienced by the cell station 800. TheCQI allows the cell station 800 to propose to an eNB an optimummodulation scheme and coding rate to use for a given radio link qualityso that the resulting transport block error rate would not exceed acertain value, such as 10%. In some embodiments, the cell station mayreport a wideband CQI value which refers to the channel quality of thesystem bandwidth. The cell station may also report a sub-band CQI valueper sub-band of a certain number of resource blocks which may beconfigured by higher layers. The full set of sub-bands may cover thesystem bandwidth. In case of spatial multiplexing, a CQI per code wordmay be reported.

In some embodiments, the PMI may indicate an optimum precoding matrix tobe used by the eNB for a given radio condition. The PMI value refers tothe codebook table. The network configures the number of resource blocksthat are represented by a PMI report. In some embodiments, to cover thesystem bandwidth, multiple PMI reports may be provided. PMI reports mayalso be provided for closed loop spatial multiplexing, multi-user MIMOand closed-loop rank 1 precoding MIMO modes.

In some cooperating multipoint (CoMP) embodiments, the network may beconfigured for joint transmissions to a cell station in which two ormore cooperating/coordinating points, such as remote-radio heads (RRHs)transmit jointly. In these embodiments, the joint transmissions may beMIMO transmissions and the cooperating points are configured to performjoint beamforming.

LTE Channel Estimation

To facilitate the estimation of the channel characteristics LTE usescell specific reference signals (i.e., pilot symbols) inserted in bothtime and frequency. These pilot symbols provide an estimate of thechannel at given locations within a subframe. Through interpolation itis possible to estimate the channel across an arbitrary number ofsubframes. The pilot symbols in LTE are assigned positions within asubframe depending on the eNodeB cell identification number and whichtransmit antenna is being used, as shown in the figure below. The uniquepositioning of the pilots ensures that they do not interfere with oneanother and can be used to provide a reliable estimate of the complexgains imparted onto each resource element within the transmitted grid bythe propagation channel.

To minimize the effects of noise on the pilot estimates, the leastsquare estimates are averaged using an averaging window. This simplemethod produces a substantial reduction in the level of noise found onthe pilots. There are two pilot symbol averaging methods available.

Time averaging is performed across each pilot symbol carryingsubcarrier, resulting in a column vector containing an average amplitudeand phase for each reference signal carrying subcarrier.

All the pilot symbols found in a subcarrier are time averaged across allOFDM symbols, resulting in a column vector containing the average foreach reference signal subcarrier, The averages of the pilot symbolsubcarriers are then frequency averaged using a moving window of maximumsize.

In some embodiments, The PSS and SSS provide the cell station with itsphysical layer identity within the cell. The signals may also providefrequency and time synchronization within the cell. The PSS may beconstructed from Zadoff-Chu (ZC) sequences and the length of thesequence may be predetermined (e.g., 62) in the frequency domain. TheSSS uses two interleaved sequences (i.e., maximum length sequences(MLS), SRGsequences or m-sequences) which are of a predetermined length(e.g., 31). The SSS may be scrambled with the PSS sequences thatdetermine physical layer ID. One purpose of the SSS is to provide thecell station with information about the cell ID, frame timing propertiesand the cyclic prefix (CP) length. The cell station may also be informedwhether to use TDD or FD. In FDD, the PSS may be located in the lastOFDM symbol in first and eleventh slot of the frame, followed by the SSSin the next symbol. In TDD, the PSS may be sent in the third symbol ofthe 3rd and 13th slots while SSS may be transmitted three symbolsearlier. The PSS provided the cell station with information about towhich of the three groups of physical layers the cell belongs to (3groups of 168 physical layers). One of 168 SSS sequences may be decodedright after PSS and defines the cell group identity directly.

In some embodiments, the cell station may be configured in one of 8“transmission modes” for PDSCH reception:; Mode 1: Single antenna port,port 0; Mode 2: Transmit diversity; Mode 3: Large-delay CDD; Mode 4:Closed-loop spatial multiplexing; Mode 5: MU-MIMO; Mode 6: Closed-loopspatial multiplexing, single layer; Mode 7: Single antenna port, cellstation-specific RS (port 5); Mode 8 (new in Rel-9): Single ordual-layer transmission with cell station -specific RS (ports 7 and/or8). The CSI-RS are used by the cell station for channel estimates (i.e.,CQI measurements). In some embodiments, the CSI-RS are transmittedperiodically in particular antenna ports (up to eight transmit antennaports) at different subcarrier frequencies (assigned to the cellstation) for use in estimating a MIMO channel. In some embodiments, acell station-specific demodulation reference signal (e.g., a DM-RS) maybe precoded in the same way as the data when non-codebook-basedprecoding is applied.

EXAMPLES

1. An example device comprising:

-   -   a transceiver;    -   a processor; and    -   a memory having instructions for execution by the processor to:        -   receive an indication of a subset of scheduling constraints            for interference mitigation and cancelation; and        -   perform interference mitigation and cancelation utilizing            the subset of scheduling constraints.

2. The example device of example 1 wherein the indication comprises anindex corresponding to a subset of available scheduling parameters to beused in the performance of interference mitigation and cancelation.

3. The example device of example 2 wherein the processor further usesthe index to access a table with multiple indexed sets of modulationcoding scheme/resource combinations.

4. The example device of example 3 wherein the subset of modulationcoding scheme/resource combinations comprise at least two modulationcoding scheme/resources selected from the group consisting of MCS(modulation coding scheme), precoding (PMI—precoding matrix indicator)and frequency-time resources.

5. The example device of example 1 wherein the scheduling constraintsspecify that co-scheduled user equipment radio bands are totallyoverlapping.

6. The example device of example 5 wherein the scheduling constraintsspecify that co-scheduled user equipment radio bands are permitted tostart from a mid-point of a radio band allocation and that the radiobands are continuous.

7. The example device of example 1 wherein the scheduling constraintsspecify that modulation orders of co-scheduled user equipment are withina limited range.

8. The example device of example 1 wherein the scheduling constraintsspecify that transmission modes are within a limited number ofcombinations.

9. The example device of example 1 wherein the scheduling constraintsspecify that a number of co-scheduled user equipment is limited.

10. An example method comprising:

-   -   receiving at a user equipment an indication of a subset of        scheduling constraints for interference mitigation and        cancelation; and performing interference mitigation and        cancelation utilizing the subset of scheduling constraints.

11. The example method of example 10 wherein the indication comprises anindex corresponding to a subset of available scheduling parameters to beused in the performance of interference mitigation and cancelation.

12. The example method of example 11 and further comprising using theindex to access a table with multiple indexed sets of modulation codingscheme/resource combinations.

13. The example method of example 12 wherein the subset of modulationcoding scheme/resource combinations comprise at least two modulationcoding scheme/resources selected from the group consisting of MCS(modulation coding scheme), precoding (PMI—precoding matrix indicator)and frequency-time resources.

14. The example method of example 10 wherein the scheduling constraintsfor interference mitigation and cancelation are received by the userequipment in an interference-cooperation region between neighboringcells.

15. The example method of example 10 and further comprising:

-   -   exchanging information identifying an interference-cooperation        region between neighboring cells; and    -   synchronizing scheduling constraints to propagate to user        equipment in the interference-cooperation region.

16. The example method of example 15 wherein one scheduling constraintincludes a radio band allocation starting from a specified set of radiobands.

17. The example method of example 15 wherein one scheduling constraintincludes all user equipment within the interference-cooperation regionusing phase-shift keying.

18. An example base station comprising:

-   -   a transceiver;    -   a processor; and    -   a memory having instructions for execution by the processor to:        -   identify a subset of scheduling constraints for interference            mitigation and cancelation; and        -   send an indication of the subset of scheduling constraints            to multiple user equipment within a cell of the base station            to enable the user equipment to perform interference            mitigation and cancelation utilizing the subset of            scheduling constraints.

19. The example base station of example 18 and wherein the processorfurther:

-   -   exchanges information identifying an interference-cooperation        region between neighboring cells; and    -   synchronizes scheduling constraints to propagate to user        equipment in the interference-cooperation region.

20. The example base station of example 15 wherein one subset ofscheduling constraint includes a radio band allocation starting from aspecified set of radio bands and that all user equipment within theinterference-cooperation region use phase-shift keying.

In various embodiments, the scheduling constraint is onmodulation/TM/MCS/PMI. In one example, the coordinated parameters arewithin a limited boundary of each other (as compared to the number ofpossibilities if there is no such coordination).

2-3 bits may be used to index into tables to limit the differencebetween co-scheduled UEs. The tables may be used to select a combinationto limit the possible combinations between co-scheduled UEs (or the UEsscheduled on similar resources in a neighboring cell). So that an UE canfigure out easily the scheduling combinations of the interferingsignals. The set of tables may be used to limit the combination, withemphasis on modulation order, transmission mode and power difference,etc. Note the tables themselves have certain flexibility to accommodatechanges. For example, in FIG. 5 “×dB” is used. Coordination may also bedone across cells on an interference coordination region.

The foregoing description of one or more implementations providesillustration and description, but is not intended to be exhaustive or tolimit the scope of the invention to the precise form disclosed.Modifications and variations are possible in light of the aboveteachings or may be acquired from practice of various implementations ofthe invention.

1. A device comprising: a transceiver; a processor; and a memory havinginstructions for execution by the processor to: receive an indication ofa subset of scheduling constraints for interference mitigation andcancelation; and perform interference mitigation and cancelationutilizing the subset of scheduling constraints.
 2. The device of claim 1wherein the indication comprises an index corresponding to a subset ofavailable scheduling parameters to be used in the performance ofinterference mitigation and cancelation.
 3. The device of claim 2wherein the processor further uses the index to access a table withmultiple indexed sets of subsets of scheduling constraints correspondingto modulation/transmission mode/modulation coding scheme/precodingmatrix indicator.
 4. The device of claim 3 wherein the subset ofmodulation coding scheme/resource combinations comprise at least twomodulation coding scheme/resources selected from the group consisting ofMCS (modulation coding scheme), precoding (PMI—precoding matrixindicator) and frequency-time resources.
 5. The device of claim 1wherein the scheduling constraints specify that co-scheduled userequipment radio bands are totally overlapping.
 6. The device of claim 5wherein the scheduling constraints specify that co-scheduled userequipment radio bands are permitted to start from a mid-point of a radioband allocation and that the radio bands are continuous.
 7. The deviceof claim 1 wherein the scheduling constraints specify that modulationorders of co-scheduled user equipment are within a limited range.
 8. Thedevice of claim 1 wherein the scheduling constraints specify thattransmission modes are within a limited number of combinations.
 9. Thedevice of claim 1 wherein the scheduling constraints specify that anumber of co-scheduled user equipment is limited.
 10. A methodcomprising: receiving at a user equipment an indication of a subset ofscheduling constraints for interference mitigation and cancelation; andperforming interference mitigation and cancelation utilizing the subsetof scheduling constraints.
 11. The method of claim 10 wherein theindication comprises an index corresponding to a subset of availablescheduling parameters to be used in the performance of interferencemitigation and cancelation.
 12. The method of claim 11 and furthercomprising using the index to access a table with multiple indexed setsof modulation coding scheme/resource combinations.
 13. The method ofclaim 12 wherein the subset of modulation coding scheme/resourcecombinations comprise at least two modulation coding scheme/resourcesselected from the group consisting of MCS (modulation coding scheme),precoding (PMI—precoding matrix indicator) and frequency-time resources.14. The method of claim 10 wherein the scheduling constraints forinterference mitigation and cancelation are received by the userequipment in an interference-cooperation region between neighboringcells.
 15. The method of claim 10 and further comprising: exchanginginformation identifying an interference-cooperation region betweenneighboring cells; and synchronizing scheduling constraints to propagateto user equipment in the interference-cooperation region.
 16. The methodof claim 15 wherein one scheduling constraint includes a radio bandallocation starting from a specified set of radio bands.
 17. The methodof claim 15 wherein one scheduling constraint includes all userequipment within the interference-cooperation region using phase-shiftkeying.
 18. A base station comprising: a transceiver; a processor; and amemory having instructions for execution by the processor to: identify asubset of scheduling constraints for interference mitigation andcancelation; and send an indication of the subset of schedulingconstraints to multiple user equipment within a cell of the base stationto enable the user equipment to perform interference mitigation andcancelation utilizing the subset of scheduling constraints.
 19. The basestation of claim 18 and wherein the processor further: exchangesinformation identifying an interference-cooperation region betweenneighboring cells; and synchronizes scheduling constraints to propagateto user equipment in the interference-cooperation region.
 20. The basestation of claim 15 wherein one subset of scheduling constraint includesa radio band allocation starting from a specified set of radio bands andthat all user equipment within the interference-cooperation region usephase-shift keying.